The United States Numbered Highway System (often called U.S. Routes or U.S. Highways) is an integrated network of
roads and
highways numbered within a nationwide grid in the
contiguous United States. As the designation and numbering of these highways were coordinated among the states, they are sometimes called Federal Highways, but the roadways were built and have always been maintained by
state or
local governments since their initial designation in 1926.

The route numbers and locations are coordinated by the
American Association of State Highway and Transportation Officials (AASHTO).[4] The only federal involvement in AASHTO is a nonvoting seat for the
United States Department of Transportation. Generally, most north-to-south highways are odd-numbered, with the lowest numbers in the east, and the highest in the west. Similarly, east-to-west highways are typically even-numbered, with the lowest numbers in the north, and the highest in the south. Some exceptions exist, however, such as spur routes. Major north–south routes have numbers ending in "1" or "5", while major east–west routes have numbers ending in "0".[1] Three-digit numbered highways are generally spur routes of parent highways (thus
U.S. Route 264 [US 264] is a spur off
US 64). Some
divided routes (such as
US 19E and
US 19W) exist to provide two alignments for one route. Special routes, which can be labeled as alternate, bypass or business, depending on the intended use, provide a parallel routing to the mainline U.S. Highway.

Before the U.S. Routes were designated,
auto trails designated by auto trail associations were the main means of marking roads through the United States. In 1925, the Joint Board on Interstate Highways, recommended by the
American Association of State Highway Officials (AASHO), worked to form a national numbering system to rationalize the roads. After several meetings, a final report was approved by the
U.S. Department of Agriculture in November 1925. They received complaints from across the country about the assignment of routes, so the board made several modifications; the U.S. Highway System was approved on November 11, 1926. As a result of compromises made to get the U.S. Highway System approved, many routes were divided, with alignments to serve different towns. In subsequent years, AASHTO called for such splits to be eliminated.

Expansion of the U.S. Highway System continued until 1956, when the
Interstate Highway System was laid out and began construction under the administration of President
Dwight D. Eisenhower. After construction was completed, many U.S. Routes were replaced by Interstate Highways for through traffic. Despite the Interstate System, U.S. Highways still form many important regional connections, and new routes are still being added.

System details

In general, U.S. Routes do not have a minimum design standard, unlike the later
Interstate Highways, and are not usually built to
freeway standards. Some stretches of U.S. Routes do meet those standards. Many are designated using the
main streets of the cities and towns through which they run. New additions to the system, however, must "substantially meet the current
AASHTO design standards".[4] As of 1989, the United States Numbered Highways system had a total length of 157,724 miles (253,832 km).[3]

Except for
toll bridges and
tunnels, very few U.S. Routes are
toll roads. AASHTO policy says that a toll road may only be included as a
special route, and that "a toll-free routing between the same termini shall continue to be retained and marked as a part of the U.S. Numbered System."[4]U.S. Route 3 (US 3) meets this obligation; in
New Hampshire, it does not follow tolled portions of the
Everett Turnpike. But US Routes in the system do use parts of five toll roads:[5]

Numbering

U.S. Routes in the
contiguous United States follow a grid pattern, in which odd-numbered routes run generally north to south and even-numbered routes run generally east to west, though spur routes can be either-or. Usually, one- and two-digit routes are major routes, and three-digit routes are numbered as shorter spur routes from a main route (with some exceptions such as
US 151, which is a main line highway). Odd numbers generally increase from east to west;
U.S. Route 1 (US 1) follows the Atlantic Coast and
US 101 follows the Pacific Coast. (US 101 is one of the many exceptions to the standard numbering grid; its first "digit" is "10", and it is a main route on its own and not a spur of US 1.) Even numbers tend to increase from north to south;
US 2 closely follows the Canadian border, and
US 98 hugs the Gulf Coast. The longest routes connecting major cities are generally numbered to end in a 1 or a 0,[6] however extensions and truncations have made this distinction largely meaningless. [7] These guidelines are very rough, and exceptions to all of the basic numbering rules exist all over the U.S. and are too numerous to list.

In the 1950s, the numbering grid for the new Interstate Highway System was established as intentionally opposite from the US grid insofar as the direction the route numbers increase. Interstate Highway numbers increase from west-to-east and south-to-north, to keep identically numbered routes geographically apart in order to keep them from being confused with one another,[7] and it omits 50 and 60 which would potentially conflict with
US 50 and
US 60.[c]

In the US Highway system, three-digit numbers are assigned to spurs of one or two-digit routes.
US 201, for example, splits from
US 1 at
Brunswick, Maine, and runs north to Canada.[8] Not all spurs travel in the same direction as their "parents"; some are connected to their parents only by other spurs, or not at all, instead only traveling near their parents, Also, a spur may travel in different cardinal directions than its parent, such as
US 522, which is a north-south route, unlike its parent
US 22, which is east-west. As originally assigned, the first digit of the spurs increased from north to south and east to west along the parent; for example,
US 60 had spurs, running from east to west, designated as
US 160 in
Missouri,
US 260 in
Oklahoma,
US 360 in
Texas, and
US 460 and
US 560 in
New Mexico.[9] As with the two-digit routes, three-digit routes have been added, removed, extended and shortened; the "parent-child" relationship is not always present.[8][10]

AASHTO guidelines specifically prohibit
Interstate Highways and U.S. Routes from sharing a number within the same state.[11] As with other guidelines, exceptions exist across the U.S. [10]

Some two-digit numbers have never been applied to any U.S. Route, including 39, 47, 86 and 88.

Signage

Route numbers are displayed on a distinctively-shaped white shield with large black numerals in the center. Often, the shield is displayed against a black square or rectangular background. Each state manufactures their own signage, and as such subtle variations exist all across the United States. Individual states may use cut-out or rectangular designs, some have black outlines, and California prints the letters "US" above the numerals. One- and two-digit shields generally feature the same large, bold numerals on a square-dimension shield, while 3-digit routes may either use the same shield with a narrower font, or a wider rectangular-dimension shield. Special routes may be indicated with a banner above the route number, or with a letter suffixed to the route number. Signs are generally displayed in several different locations. First, they are shown along the side of the route at regular intervals or after major intersections (called
reassurance markers), which shows the route and the nominal direction of travel. Second, they are displayed at intersections with other major roads, so that intersecting traffic can follow their chosen course. Third, they can be displayed on large green
guide signs that indicate upcoming interchanges on freeways and expressways.

Various U.S. highway sign designs

Most commonly used one- or two-digit variant, standard shield on a black square

Three-digit variant, square proportions and thin font

Three-digit variant, rectangular proportions and standard font

Outline variant

California variant, with US at top and black outline

Florida variant, in color, now retired

Historic design, with state name and US on shield, block-style font, now retired

Alternate route, with full-size letter suffix

Business route, with small letter suffix

Alternate route, with hyphen and full-size letter suffix

Bypass route, with "BY-PASS" written in the shield

Alternate route, with "ALT" written in the shield

Alternate route, with "ALT" written in a banner above shield

Business route, with "BUSINESS" written in a banner above shield

Divided and special routes

Since 1926, some divided routes were designated to serve related areas, and designate roughly-equivalent splits of routes. For instance,
US 11 splits into
US 11E (east) and
US 11W (west) in
Bristol, Virginia, and the routes rejoin in
Knoxville, Tennessee. Occasionally only one of the two routes is suffixed;
US 6N in
Pennsylvania does not rejoin US 6 at its west end. AASHTO has been trying to eliminate these since 1934;[12] its current policy is to deny approval of new split routes and to eliminate existing ones "as rapidly as the State Highway Department and the Standing Committee on Highways can reach agreement with reference thereto".[4]

Special routes—those with a banner such as
alternate or
bypass—are also managed by AASHTO.[4] These are sometimes designated with lettered suffixes, like A for alternate or B for business.[13]

Naming

The official route log, last published by AASHTO in 1989, has been named United States Numbered Highways since its initial publication in 1926. Within the route log, "U.S. Route" is used in the table of contents, while "United States Highway" appears as the heading for each route. All reports of the Special Committee on Route Numbering since 1989 use "U.S. Route", and federal laws relating to highways use "United States Route" or "U.S. Route" more often than the "Highway" variants.[14] The use of U.S. Route or U.S. Highway on a local level depends on the state, with some states such as Delaware using "route" and others such as Colorado using "highway".[15][16]

History

Early auto trails

In 1903,
Horatio Nelson Jackson became the first documented person to drive an automobile from
San Francisco to
New York using only a connection of dirt roads, cow paths, and railroad beds. His journey, covered by the press, became a national sensation and called for a system of long distance roads.[17]

In the early 1910s,
auto trail organizations—most prominently the
Lincoln Highway—began to spring up, marking and promoting routes for the new recreation of long-distance automobile travel. While many of these organizations worked with towns and states along the route to improve the roadways, others simply chose a route based on towns that were willing to pay dues, put up signs, and did little else.[1]

Secretary
Howard M. Gore appointed the Joint Board on Interstate Highways, as recommended by AASHO, on March 2, 1925. The Board was composed of 21 state highway officials and three federal
Bureau of Public Roads officials. At the first meeting, on April 20 and 21, the group chose the name "U.S. Highway" as the designation for the routes. They decided that the system would not be limited to the federal-aid network; if the best route did not receive federal funds, it would still be included. The tentative design for the
U.S. Highway shield was also chosen,[20] based on the shield found on the
Great Seal of the United States.[1]

The auto trail associations rejected the elimination of the highway names. Six regional meetings were held to hammer out the details—May 15 for the
West, May 27 for the
Mississippi Valley, June 3 for the
Great Lakes, June 8 for the
South, June 15 for the
North Atlantic, and June 15 for
New England. Representatives of the auto trail associations were not able to formally address the meetings. However, as a compromise, they talked with the Joint Board members. The associations finally settled on a general agreement with the numbering plans, as named trails would still be included. The tentative system added up to 81,000 miles (130,000 km), 2.8% of the public road mileage at the time.[1]

The second full meeting was held August 3 and 4, 1925. At that meeting, discussion was held over the appropriate density of routes.
William F. Williams of
Massachusetts and
Frederick S. Greene of New York favored a system of only major transcontinental highways, while many states recommended a large number of roads of only regional importance. Greene in particular intended New York's system to have four major through routes as an example to the other states. Many states agreed in general with the scope of the system, but believed the
Midwest to have added too many routes to the system. The group adopted the shield, with few modifications from the original sketch, at that meeting, as well as the decision to number rather than name the routes. A preliminary numbering system, with eight major east–west and ten major north–south routes, was deferred to a numbering committee "without instructions".[1]

After working with states to get their approval, the committee expanded the highway system to 75,800 miles (122,000 km), or 2.6% of total mileage, over 50% more than the plan approved August 4. The skeleton of the numbering plan was suggested on August 27 by
Edwin Warley James of the BPR, who matched
parity to direction, and laid out a rough grid. Major routes from the earlier map were assigned numbers ending in 0, 1 or 5 (5 was soon relegated to less-major status), and short connections received three-digit numbers based on the main highway from which they spurred. The five-man committee met September 25, and submitted the final report to the Joint Board secretary on October 26.[1] The board sent the report to the Secretary of Agriculture of October 30, and he approved it November 18, 1925.[9]

Disagreement and refinement, 1925–26

The "final" U.S. Highway plan as approved November 11, 1926

The new system was both praised and criticized by local newspapers, often depending on whether that city was connected to a major route. While the
Lincoln Highway Association understood and supported the plan, partly because they were assured of getting the
US 30 designation as much as possible, most other trail associations lamented their obsolescence. At their January 14–15, 1926 meeting, AASHO was flooded with complaints.[1]

In the Northeast, New York held out for fewer routes designated as US highways. The Pennsylvania representative, who had not attended the local meetings, convinced AASHO to add a dense network of routes, which had the effect of giving six routes termini along the state line. (Only
US 220 still ends near the state line, and now it ends at an intersection with future
I-86.) Because
US 20 seemed indirect, passing through
Yellowstone National Park,
Idaho and
Oregon requested that
US 30 be swapped with US 20 to the
Pacific coast.[1]

Many local disputes arose related to the committee's choices between designation of two roughly equal parallel routes, which were often competing auto trails. At their January meeting, AASHO approved the first two of many split routes (specifically
US 40 between
Manhattan, Kansas and
Limon, Colorado and
US 50 between
Baldwin City, Kansas and
Garden City, Kansas). In effect, each of the two routes received the same number, with a directional suffix indicating its relation to the other. These splits were initially shown in the log as—for instance—US 40 North and US 40 South, but were always posted as simply US 40N and US 40S.[1]

The most heated argument, however, was the issue of US 60. The Joint Board had assigned that number to the Chicago-Los Angeles route, which ran more north–south than west–east in Illinois, and then angled sharply to the southwest to
Oklahoma City, from where it ran west to
Los Angeles.
Kentucky strongly objected to this designated route, as it had been left off any of the major east-west routes, instead receiving the
US 62 designation. In January 1926, the committee designated this, along with the part of
US 52 east of
Ashland, Kentucky, as
US 60. They assigned US 62 to the Chicago-Los Angeles route, contingent on the approval of the states along the former US 60. But Missouri and Oklahoma did object—Missouri had already printed maps, and Oklahoma had prepared signs. A compromise was proposed, in which US 60 would split at
Springfield, Missouri, into US 60E and US 60N, but both sides objected. The final solution resulted in the assignment of
US 66 to the Chicago-Los Angeles portion of the US highway, which did not end in zero, but was still seen as a satisfyingly round number.[1] Route 66 came to have a prominent place in popular culture, being featured in song and films.

With 32 states already marking their routes, the plan was approved by AASHO on November 11, 1926.[1] This plan included a number of directionally split routes, several discontinuous routes (including
US 6,
US 19 and
US 50), and some termini at state lines.[21] By the time the first route log was published in April 1927, major numbering changes had been made in Pennsylvania in order to align the routes to the existing auto trails.[22] In addition,
U.S. Route 15 had been extended across
Virginia.[23]

Much of the early criticism of the U.S. Highway System focused on the choice of numbers to designate the highways, rather than names. Some thought a numbered highway system to be cold compared to the more colorful names and historic value of the auto trail systems. The New York Times wrote, "The traveler may shed tears as he drives the
Lincoln Highway or dream dreams as he speeds over the
Jefferson Highway, but how can he get a 'kick' out of 46, 55 or 33 or 21?"[24] (A popular song later promised, "Get your kicks on Route 66!") The writer
Ernest McGaffey was quoted as saying, "Logarithms will take the place of legends, and 'hokum' for history."[1]

Expansion and adjustment, 1926–56

When the U.S. numbered system was started in 1925, a few optional routings were established which were designated with a suffixed letter after the number indicating "north", "south", "east", or "west". While a few roads in the system are still numbered in this manner, AASHO believes that they should be eliminated wherever possible, by the absorption of one of the optional routes into another route.

In 1934, AASHO tried to eliminate many of the split routes by removing them from the log, and designating one of each pair as a three-digit or alternate route, or in one case
US 37. AASHO described its renumbering concept in the October 1934 issue of American Highways:[12]

"Wherever an alternate route is not suitable for its own unique two-digit designation, standard procedure assigns the unqualified number to the older or shorter route, while the other route uses the same number marked by a standard strip above its shield carrying the word 'Alternate'."

Interstate era, 1956–present

1961 version of the U.S. Route shield

The
Federal Aid Highway Act of 1956 appropriated funding for the Interstate Highway System, to construct a vast network of
freeways across the country. By 1957, AASHO had decided to assign a new grid to the new routes, to be numbered in the opposite directions as the U.S. Highway grid. Though the Interstate numbers were to supplement, rather than replace, the U.S. Route numbers, in many cases (especially in the
West) the US highways were rerouted along the new Interstates.[10] Major decommissioning of former routes began with
California's
highway renumbering in 1964. The 1985 removal of
US 66 is often seen as the end of an era of US highways.[28]

A few major connections not served by Interstate Highways include US 6 from Hartford, Connecticut, to Providence, Rhode Island and US 93 from Phoenix, Arizona to Las Vegas, Nevada, though the latter is planned to be upgraded to
Interstate 11. Three state capitals in the contiguous U.S. are served only by U.S. Routes:
Dover, Delaware;
Jefferson City, Missouri; and
Pierre, South Dakota.

In 1995 the
National Highway System was defined to include both the Interstate Highway System and other roads designated as important to the nation's economy, defense, and mobility.

AASHTO is in the process of eliminating all
intrastate U.S. Highways less than 300 miles (480 km) in length "as rapidly as the State Highway Department and the Standing Committee on Highways of the American Association of State Highway and Transportation Officials can reach agreement with reference thereto". New additions to the system must serve more than one state and "substantially meet the current
AASHTO design standards".[4] A version of this policy has been in place since 1937.[29]

The 1925 routes

The original major transcontinental routes in 1925, along with the
auto trails which they roughly replaced, were as follows:[1][9]

US 10, US 60, and US 90 only ran about two thirds of the way across the country, while US 11 and US 60 ran significantly diagonally. US 60's violation of two of the conventions would prove to be one of the major sticking points; US 60 eventually was designated as US 66 in 1926, and later it became popular in the culture. US 101 continues east and then south to end at
Olympia, Washington.[21] The western terminus of US 2 is now at
Everett, Washington.[8]